Combustion control



Oct. 1, 1929. F 5. BENNETT ETAL 1,729,701

COMBUSTION CONTROL Filed Dec. 1926 Z3 I Inventors:

: I Frank S. Bennett, Leonard R. B1225,

y ww Their AttOTfiQyp particular application.

' i of a ratchet mechanism.

FRANK-S. nnmmrn'or scnENEcrAnY, Ann LEONARD 3. Brass, on-scozrrm-nnw YORK, As'sIeNoRs', BY 'MESNE ASSIGNMENTS, 'ro nanny .-METER COMPANY, A

, eonrona'rxorf or DELAWARE 19 this is'only by way ofexam'ple and that the invention is not limited necessarily to-this-J The object ofthejinvention is to providev an improyed system of control-which gives 15 good regulation and" which automatically -takes care of I Various operating; conditions met with, and for a consideration of what we believe to be-'-novel andfour invention, attention 'is directed to the accompanying description and the claimsappended thereto.

- In; the drawing, Fig. 1'is a diagrammatic view of a combustioncontrol systemembo'dy ing he inventiorn and Fig.2 is'adetailv'i'ew Referring to the drawing, 1 indicates a boiler, forexample ast'eam boiler, having a vapor drum 2 from which vapor is conveyed by a conduit '3 ma header-4;.- Header may 'be a header 'common'to the'seyeral boilers of '30 the plant, -5 indic'atin a conduit conveying vapor from the vaporrum of another boiler to header 4. 6 indicatesa fuel feeding means such as a stoker mechanism for supplying'fuel to the furnace of boiler 1, and v7 indicates an .electric motor for driving the fuel feeding mea1is.- The armature of motor-I7 is connected .to' a suitable source of electrical energy by v leads 8, and its field winding 9 is chnnected into a control circuit as will be'explained.here-- inafter. The fuel-supplied-to the-furnace by the fuel feeding means 6 is proportional to the speed of the motor 7.- 1 0 indicatesa' blower for supplying] air. to the furnace. It maybe of any suitable type and is driven by an elec-' trio-motor 11. 12 indicates the leads for the field of motor 11 They may be connectedto any 'suitable source of electrical energy. Con nected witlrthe armature of'motor 11 is a resistance 12 adaptedto be 'cut into and out .of circuit by an arm 13 which travels up and 'similangear Wheel 16 ontheend of the shaft 'adirection to cutresistanc'e out of the armagdriven 'and ethus motor 17 forms aregulating source ofeleCt-ricalienerg in the present in a plication thee- December 351m serial 152,506.

down a threaded rod 14, "the arm 'cuttingthe i resistance into and out of circuit a notch at a time. On the' loweren'd'of rod 14: is a,

bevel a gear wheel -15, which --meshes with a of a motor 1 7."- Motor 17 has two field windings 18 and 19. When current flows through 'o neof these fie'ld' windings, the Winding 18 in the present instance, motor 17'is operated in 6O tui'e-circuitof'motor 11 thus eiiecting'an in 4 crease inv the speed-of motor '11 while when it flows through the other field winding, i. e., windingv 19,.motor 17 is operated in'a direc-- tion to cut resistanceinto the armature ci rcuit "of ;-motor 11 thus effecting a] decrease in the speed or motor'l-l: The volume of air supplied-tothe furnace by blower 10 is pro'-' portional to the speed at which the blower is means whereby the amount of air supplied to the furnace may be increased and decreased. v

' 20 and 21 indi'catelead lines of a suitable stance alternatingcurrent, and-22 and 23 indicalte lead lines of-a source of electrical en- .ergywhichin the ,of direct current.

present instance is a source Connected to conduit '3 is a flow meter 'M which feflfects the production of electric 'cur rent which bears a definite relation to the rate of flow of vapors in. the conduit. In'the present instance, it is shown as beingafiow meter 0f the type disclosed thc'patent to Th'ompson andli'liclil'airy,No..1,560,9 61patentedllovember 10, 1925,;this beinga now known 't' peof flow meter. 24indicates aprgssure di eren'ce creating de ice'for the'fiow meter, 25 and 26 t'he leading. and trailing pressure connections, and 27 a winding which in thetype .of flow meter illustrated, forms the primary winding of a transformer, the 'secondary "winding of which-is formed by amercury' ring in the flow meter casing; One; terminal of winding 27 is connected by a con-' "duotor 28 to line wire 20 the otherter'minalis connected to line wire 21- by way of conductor 29,solenoid winding 30, conductor31, solenoid winding 32, conductor 33, rheostat' lever '34, resistance 35, conductor 36 and conductor 37. 9

' There is thus in this circuit' including sole noid windings "and 32 a flow'of electric curlated'fom the shaft. Also. carried -byj'this i rent which'isa measure of the flow of vapor 'through conduit 3. This circuit may be termed thevapor flow or steam flow circuit. Connected to boiler 1 is an'electrie flow meter N for measuring the amount of,air.fiowingthrough the furnace. It may be of any suitable type. In the present. instance, there is indicated an electric. flow meter of the type disclosed in the application of L'; W. Thompson, Sr.-No.1742,22 0,' filed Oct 7, 1924. nIt comprises a casing 38 which contains a'movcable element which may be in the form'of an inverted bell 39, the lower edge of the bell being sealed in a liquid contained in an an-.,. nular chamber 40. The opposite sides of hell 39' are connected by leading and trailing of flow of ases through the furnace. Belly pressure pipes 41 and 42 to suitable points in the furnace of suchcharacter'that therewill be a drop in'pressure between the connections which will bear adefinite relation to the rate 39 ispivota ly connected to a lever 43 which atone end is pivoted on a fixed post-44. .The

- other end of lever 43 is connected by link 45 to an armature 46 on' which is a closed winding47; In operative relation to armature 46 is a fieldstructure comprising a winding 48. The flow meter mechanism illustrated serves to effect oscillating movementof armature 46 in response to changes in the rate of flow of 'gas through the boiler and such oscillating movementjyaries the current in the circuit of field-winding 48 an amount proportional to o'the'movement,'providing therefore a current which-is a'mea'sure-of the air passing through the furnace. The electric flow meter here illustrated-is shown'only diagrammatically and by way of'example. It is to be taken as typical of any suitable electric flow meter. 'Furthermore, its mode of operation is not explained in detail because it is now akno'wn type of-flow meter which may be purchased on the market. As already stated, the essential thing is that it be an instrument capable of producing a flow of electric current which is a measure of. the air flow through the furnace.' One terminal offield winding:48 is connected 'by a conductor-49 to line'wire 20-the other terminal beingconnected to line .wire2 1 byconductor 50, solenoid winding 51', conduc- 'tor'52, rheostat arm 53, resistance 54', conduc tor 55 and conductor-37. r Th'ere thus flows in l v this circuit and in the solenoid winding 51 an One terminal of field winding 9 of fuel supply motor 7 is connected by conductors 56 and 57 to line wire 22. The other terminal is connected to line wire 23, by conductor 58, rheo-' stat arm 59, resistance 60, conductor 61, conductor 62, and conductor63. Rheostat arm 595s carried by a shaft on which is a bevel {'ge'arwh'eu 64, the arin being suitably insusame -"shaft is an insulated rheostat arm,

which cooperatesv with the electrical resisttruce/'66; One tei'ininal'ofelectrical resistance 66is connected by' a conductor 67 t line wire .wire 21. byffrheostatarm .65, conductor 68,

20, the other terminal being connectedto lin'e solenoid winding 69, conductor 7 O, resistance "71, rheostat arm 72, comluctQr 73,-';rheost-at arm;74,,res'istance 75, conductor 76 and conductor37.1;Qdrmected'to bevel gear wheel 64 a bevel gear-wheel77 "carried by the shaft of an'electri'emotor 78. "Motor-78 has two field windings79=and 80'. When a. circuit is closed on one'of these windings, it operates motor 78in adirection to move simultane-i 'ously-rheo s't'at arms 59 and 65 ina direction to increase theQamount-of the resistance60f in circuit with motor field 9 and decrease the traced through-solenoid winding 69. On the other hand, when a 'c ircuit' isclosed through operatedi n' adirection'to decrease the amount ance 66 in the circuit including solenoid windmg 69. Resistance 60 serves to regulate the speed-of stoker motor 7. -When the amount of resistance.60 in circuit withfield winding9- is increased the fieldis' weakned whereby the speed of the motoris, increased to increase the amount 1 of fuel supplied to the furnace. On the other hand, when'ftheamount of resis'tance 60 in circuit with thefield winding 9 is decreased, the fieldis strengthened there-'- '85 amountof the-resistance 66in the-circuit ust bydecreasing the speed of the fuel feed motor 7. As will be noted, the arrangement of resistance 66' is such thatgwl'ienmotor 78 operates in aidirection to increase the speed of the fuel feed motor, rheostatl 'arm .65 ismovedin a'directionto decrease theamount' of resistsince 66 in circuit and thus ncrease the current flowing in the circuitof solenoid 69, and when motor .78 moves rheostat arm 59in a direction-to' decrease the speed: of fuelifced mo-.

tor 7, then rheostat ar'm-65is moved inadireci tion to increase theamount ofre'sistance 66in.

circuit, thereby decreasin "theamount of ciir- 11 rent flowing through so enoid '69.; 1 The arrangement is such that the current flow-jin'the'.

circuit including resistance- 66'. and i solenoid 69 bears alwa a definite. relati'q t g 01V.- ing through solenoidf69 the ef re varies with'l.

of the fuel feed motor- 7. The current? and forms ameasure of the fuel beingsups plied'to the furnace. termed the fuelcircuit.-

69 are connected to opposite ends of level 81 suitably'pivoted at its central point. On one end of lever 81 is a contact 82 adapted to engage a contact 83 and on the other end of lever 81 is'aconta'ct 84 adapted to engages.

This circuit may be.

The Y plungers of solenoid windings '30 and contact 85. Contact83'is connected-to one 7 terminal of field winding 80. by conductor; .65 switch-arm 87 and condu'ctor'f88. andieo'n'ltact -185 isconnected-toone terminal of field wind tor 91. The other terminalsof'fie'ld windings ing 79 by'conductoi' 89, "switch arm 90; condii 1 7 9 and 80 areconnected to line wire 22b'yve0n' windings 32an'd 51 are connected to .a lever 95 pivotedat its-,central'point and carrying the rheostat arm'72; already'irefierredto.- 'The plunger of; solenoid winding 32. is' provided with a dash pot 96 to dampen the movement of it. 5 The lower end of the plunger-for sole noid winding; 51 is providedwith a'pin' 97 3 adapted upon 'a certain' movement to movea connector .98 away froma pairfof contacts 99; 100 indicates va, press ure responsivedevice connected tohea'der i by a-pipelOl, Its purse' is to effect oscillating movement-016a shaft 1021in' response to changes in pressure in'header 4'. Any suitable arrangement for effecting oscillation of shaft.102" in response to and by amounts proportional to changes in pressure in header 4 maybe'utilizedy In the present instance, the pressure responsive device is'shown-as being in the'form of a coiled."

tubular memberha-ving one" end fixed to -a shaft 103-on whichis .a gearsegmenti104 which meshes with apinion 105-on sl1aftl02.- Uponv an increase in pressure in -header'a' I the'coiledtubular;me1nber tends to unwind A which servesto efi'ect movement of shaft- 102 in a clockwise; direction as viewed'from'the left hand end while upon a decrease in pressure in header 4 the result is to effect amoveformed by insulating material so that the two ment-of shaft 102 injan anti-clockwi'sedirec- ,tion. Fixed on shaft 102 is a contact'bridge 106 having at'its ends adjustable contacts107 and 108: Stops 108 areprovided for'limiting .the movement of bridge 106. Loosely mounted onshaft 102 is a contact bridge 109 having contacts'lIO and 111 at its two ends};

The centralportio'n' .of bridge 109 may be ends of the bridge are insulated from each other. Carried by the two ends (if-"bridge- 109 are spring contact members 112 and 113 which cooperate withametal'insets114and 115 in aniinsulating disk-116 carried by. a

.When' this takes place spring contact 113 remains inengagemen't with'metal inset 115 while spring contact 112 is moved away from metal inset lligwhen shaft 102 moves'in an anti-clockwise direction contact 107 en-.

I gagescontact :110 after which bridge 109 moves along with bridge 106 bringing spring solenoidwinding;126,

spring, contacts 112 and 113 with edge of any'--.position-.;to which it is'inoved. T Bridge ljnieinber mfisis connected toli-ne wire 22 by doctor 92. armature of motor .78, conductor-93; vand conductor 57,- Contacts 82 and-8 1fl are; con'nectedto line wire 23 by conductor 94: and. conductor 63 The Y plungers of solenoid ,line wire 23 by springcontact112, metal in-' set 114 conductor 125, solenoidwinding 126 and conductor, 127 "and contact 111 is consk 116 is; 'suchthat bridge 109 remains in necteditodine wire'23 by spring contact arm 1 13 m cta .l inset 11 5, conductor 128, solenoid winding 129 and conductor 127. Thusit will 9 be seen that whenthe-pressure inheader 4 increases, effecting a turning movement of shaft 102 in a clockwise direction, a circuit is vclosed'.through-solenoid, 129 and that when clockwise directionfa circuit is closed through Fixedon shaft102 is a segment130 havable springa-rm'132 having a contact 133 It/9 its free endyvhicl engages a'con tact 13% on the free end of a springarm 135. Movement the pressure hea'der t'decreases efiecting; a turning movement of shaft 102 in an antiing acam 'surface'dnwhich rests a roller 131. The central portionof-the cam surface is fiat of shaft-102 in either'tlirection serves to turn Y segment 130 beneath'rQ'ller 131'. =lfshaft 102 is turned to-anextent suificient to bring a cam surfaceon segment 130 beneath the roller, it serves to lift springarm 132upward, thereby tending to move contact 133 jaway from contact134. 7' Springarms .132 and 135 are fixed at. their outer ends. 136 isl' 'athreaded pin adapted to adjust the position of contact 133.

- On theunderside ofspring arm 135 is'a leaf spring 137 whichengagesthe end-of a thread ed-pin 138. -By adjusting pin 13'8vin its fixed support the upward spring pressure on spring arm'135 may be adjusted. Spring-$111135 is engaged by a cam surface-139onja'gear segment 1 10 Meshing witlrtheteeth on gear segment 140 is apiniond 'tl carried by a shaft142. v ,Shaft 142 is connected by a ball and ratchet coupling 143 toa secondshaft 144. Coupling 143 may be of usualiconstruc- 'tion as is illustrated. in Fig; Loosely mounted on shaftMA is-a' gear whee'i lfvand fixed on such shaft is a disk 146-.which formsa part of a mag'ne'ticclu'tch comprising wind; ings 147 connected 'by suitable "conductors 'to slip rings 148on shaft 144:. Bearing on sli ring 148 are eontactfingers'149 through vhic 1 an electric circuit i'sieonnected'f towinding 14;, g i

Meshing with '.-gear wheel a gear Wheel 150 which forms a part otyl the gear train of a magnetic retarding 'deviceindicated generally by reference numerals 151;

I ing device is connected toshaft144. "On the V Thewindings '147 of the magnetic clutch The magnetic retarding device maybe of any suitable construction,- in thepresent instance being shown ascomprising two electric magnets 152 connected to a-suitable source of v electric urrent and operating one disk 153 which rotates between them. 'On the outer end-of shaft 142 is a pinion 154 which meshes with a rack155 onthe upper end of 'a'solenoid plunger 156, the lower end -ofwhich carries.

connector 121. The ball andratchet connec- "tion 143 is arranged so that solenoid plunger 156 may bemoved upward freely without turning s'haft 144. It can thus move upward I independently of the "magnetic retarding I mechanism 151. On its downward move upper end of rack-155 is a weight 157 'which tends to move the rack downward;

" are-connected'into a circuit including-contacts 7 t 133 and 134 which may be traced as follows i Line wire 23, conductor158, spring arm ings 147, conductor 160, conductor'l61, and conductor 124. As longvas contacts. 133 and 134 are in engagementthis circuit through windings 147 of the magneticclutch is'closed,

this being a normal condition of this circuit.

At 162 is a solenoid winding having one terminal connected to line wire 23 by conduc-' tor 163- and conductor 127 and the other-ter- 'minal connected'to line wire 22 byconductor 164, contact 120, connector 121, contact 122,

' conductor 123 and conductor 124.-"Thus itv will be seen that a circuit is closed througlr solenoid winding 162 whenever connector 121 bridges contacts 120 and122'. The-plunger ofsolenoid 162 carries aconnector 165 which bridges a pair of contacts 166 whenever solenoid:162 is energized; 167 is a dashpotfor retarding the movement of the plunger for solenoid winding 162 in both its up and down 5 movements. lVhen solenoid winding 162 is' energized to bridge contacts 166 a circuit is closed on a solenoid winding 168 which cooperates with plunger .156 and which may be traced as follows :-Line wire 22, conductor 124, conductor 161, conductor 169, solenoid winding 168,-conductor 170, contacts 166, conductor 171 and conductor 127 to'lirie wire This serves'to energize solenoid winding 168 thereby lifting plunger 156 and moving co the connector121 away from contacts 120 -and122.-' v

Solenoid winding 126 has aplungeritowhich is connected a bridgemember 172 adapted tobridge 'contacts'173; When these 05 contacts are bridgeda circuit is closed through field winding IS of motor 17-which n 1ay be traced as follows :-Li ne. wire 22,"conducto'r '174, armature of motor 17, conductor'.175,-

field winding-18, conductor 176, switch'arm air-being suppliedto the furnace. Solenoid winding 129 has a plunger which carries a 'coiinec'tor180'adapted tobridge'a pair of contaots181 When contacts 181-are bridged" by-conne'ctor 189,v a circuit is closed through field winding" 19 of motor 17 whichmay be traced asfollows :Line wire 22, conductor 174, armature at motor 17, conductor 175,

fieldwi'nding 1.9, conductor 182,"switch arm 183, conductor 184, contacts 181 and conductor 127 to line'wire 23; \Vhenthis'circuit'is "closedit serves to operate'motori 17 in a di- .rection to. decrease the speed of 'motorll and "hence the amount'of air being supplied to the furnace. 1 v

' The switches comprising. switch arms 177 'and'183 and switch arms 87 and 90 are adapted to b'emoved into engagementewith pairs of contacts .185 .and 186 respectively, This -132,'.'contacts 1'33 and 134, spring arm 135, 3 conductor 159, contactfingers 149 and wind ser'v'es 'to throw-the control of air-regulating motor 17-and fuel regulating motor 78, to two manual switches, 187 and 18S -Whereby such control-motors may be manually operated as is obvious from an inspection of thecircuit connections. -At 189 is a manually operated two-way switch connected directly with the field windings 79 and.80 of motor 78. This permits of'a'djus'tment of the fuel manually while the automatic coiltrol is operative. If desired, a 'similar switch may be provided for motor 17 also, v

The mechanism shown in the dotted square is mechanism appurtenant to all the boilers .of the battery of boilers and maybe termed.

the air control mechanism; The mechanism at the left of thedrawing is appurtenant to no the individual boiler 1 only and operates the fuel and air supplies for it. For each of the other boilers ofthe-b'attery asimilar'me'chanism provided and'ch'arac'ter B'atzthe right hand side of the drawingindicatesmecha- I nism for, a secondboiler. Q'Whenithe air control-mechanism operates it eifectsadjustment of the air supplying means for all the boilers inthe same manner. The operation will hedescribed now forthe boiler. shown, it being understood that the description=ap- .plies also to the other boilers 'of the battery connected to the air control mechanism.

- Assume that boiler I is supplying steam at a certain rate to conduit 3 and thatthe stoker was 7 and blower motor 11 are supplying fuel and air in the quantities required to generate the steam flowing throughconduit'3 .andmaintain the desired pressure in the boiler. Under these circumstances, the cur- ,130

' rent flow through solenoid winding 30, which current is proportional to the-steam flow and .the current flowfthroughsolenoid winding 69 which1current is proportional to the fuel flow, balance. each other sojthat-contacts .82'

. and'84 are out-"ofengagement with contacts 83 and 851 as shown in the drawing; Aiso,

' the current fiowingthroug'h solenoid winding "32 which current is a-measureo'f the steam winding 51 whichcurrent isa measure ofthe air flow, balance each other and hold the'contact arm 72 in a certainposition Referring to the air control mechanism;

contacts .133 and134fare in engagement with each other, which. means that the circuit ing just bridged 'contacts120 and 122. This has closed the circuit through solenoid wind-- v y v tlon, thereby decreasing theamount of re-' ing162 and operatedits plunger so as to bring the connector 165 into engagement with contacts 166 This in turn has closed a circuit 5 through solenoidfwinding 168by' way ofline wite22,conductor124, conductor 161, conductor1 69, solenoid -winding 168, conductor 170,

contacts 166 and condiuztorsv 171 and'127 to line wire 23. Solenoid 168 is thereupon-em.-

ergiz ed} to 'liftits plunger-156 thus moving connector, 121- away from contacts 120 J and 122, The .upwardmbvementotplunger 156 takes place quickly because ot the fact that ratchet 143 permits shafts 132 to: turn independently of the magnetic retarding device 151' which is connected to shaft- Duringthis movement pinion 141 turns gearwheel 140 sov as to move cam 139 in the direction indicated by the arrow. This serves to move the'cam away' from contact-with spring arm 135. However, spring arm' 135 is .--prevented from .moving upwardby spring arm 132 which. lies above it As soon as connector 121 moves away from contacts 120 and 122, the circuit.

through solenoid'162 is opened but solenoid.

162 is retarded by dash 0t 167 so as to main-- netc brake 151, the arrangemet being such that the bottom of its-movement is reached after a predetermined interval of time.

\Vhcn it reaches the lowermost position, conncctor 121 again bridges contacts 120 and 122 whereupon the cycle of operation just described is repeated again. This operation-- goes on continuously but if the pressure in interval of.'

regulating action takes lace.- j Assume now that'the v emand for steam-decreases so that there is' a decrease inthe rate.

of steam flow .from; boiler-2. This decrease in steam .fio'w is recorded immediately on steam flow meter M, the currentthrou 'h the steam flow meter circuit which includes solenoid windings 30"and 32 being reduced to a value corresponding to the, decreased rate of steam flow. The pull of solenoid winding 30' on its plunger isthus decreased whereupcon'duit' 3zremains at the desired value no f on solenoid-winding 69 moves contact 82 into engagement with contact 83. This closes a circuit on field winding of motor 7 8 which 'circuitmay be traced as follows :Line wire, '23, conductor 63, conductor 94, lever arm 81, contacts 82 and 83, conductor 86,.switch arm 87, conductor 88, field winding 80, conductor 92, armature. of motor 7 8, conductor 93, conductor 57- to line wire 22. Motor 78 is therearms 59 and 651ina counter-clockwise direc sistance 66 in the'fuelcircuit which includes the solenoid winding 69 and-resistance 71.

upon operated in'adirection to move contact Decreasing .the amount of resistance '60 in.

the field circuit of motor 7 serves to strengthen'thc field and thereby decrease the speed of motor 7 andhence theamount'of fuel supplied to the furnace. At the same time in creasing the amount of resistance 66, in'the circuit-of solenoid winding 69 serves to'decrease the amount of current flowing in this circuit whereupon contact 82-is m'oved'from engagement with contact 83thus opening the circuit onlfield windingBO. As a result the rate at which fuel is supplied to the furnace is brought down to a value corresponding to the amount of steam being generated. V

The change incurrentvalue through solenoid winding 32 unbalancesalso the pull on A lever 95.- However, becauseof the. retarding effect of dashpot96, lever- 95 is not moved immediately- .The decrease in steam flow which has been assumedtohave taken place will be accompanied by an increase-in the'steam pressure in header-"4. This acts on pressure responsive device IQQtencling to uncoil it, thereby moving gear segment lh t'toward the right as viewed in the drawing. This turns shaft 102 in a clockwise direction, thereby bringing contact 108' into engagement w1th contact 111. At 'thesame tin1e,'cam 130 moves underroller 131, butif the change in pressure isof small value roller131 will not be lifted because of the flat central position of the cam. When solenoid plunger 156 now reaches its lowermost position, bringing c onnector 121 into engagement with contacts-122 and 120, a circuit is closed which may be traced as follows :Line wire' 22, conductor 124, con- J6 g i 1,729,?!)1

- ductor 123, contacts 122 and 120, co n(hictor conductor- 127 to 'linewire 23. When 's'olenoid- .there y closing a circuit on field winding 19 "119, conductor 118, bridge 106,,contact 108, contact 111, spring contact arm 113, contact 115, conductor 12,8, solenoid winding 129, and

winding 129 is energized-connector 180 is brou ht into engagement with'contacts 181,-

which maybe traced as follows:Line wire '22, conductor 174, armature of motor 17,

which results in decreasing, the speed of blow-f erlO and hence decreasing the amount of; air

supplied to the furnace. v v

as just explained, there will not'be effected,

under ordinary operating conditions, an unbalancingaof the pull of the two -.so'lenoid;

windings 32-and5l on'leve'r arm 95. lVhen the steam flow decreased it was followed immediately by a decrease in the flowwof current in the circuit of fiow meter Mwhich ineludes solenoid winding 32. This has a tend ency to unbalance. the pull of solenoid wind ings 32 and 51 on lever 95, tending to turn vcontact arm 72 me direction to increase the amountof resistance 71 in the fuel circuit which includes solenoid winding 69. However, retarding device 96 serves to delay this movement and since the decrease in steam flow is followed fairly promptly by a-deerease in air flow, then the balance of solenoid wind ings 51' and 32 will not be destroyed to'such an extent as to effect a change in the amount of resistance 71 in circuit. I i a When connector 121 bridges" contacts 120 and 122 to effect adjustmentof the air supply to the furnace, as just explained,it at the unit, In other words, when connector 121 bridges contacts 120. and 122 at a time when contact same time again closes the circuit on solenoid winding 162 whereby causing connector165 to bridge contacts 166 and again close the circuit onsoIenoidwinding 168, as explained above. Dashpot 167' serves to retard the upward movement of connector 165 so that the circuit through solenoid winding 168 is not closed until after a predeterminedinten val of time, such time interval being sufficient to permit of or'efi'ect the desired adjustmentof the air supply. For example, the interval may be of'a length such-as to effect an ad'- ustment of resistance 12' one notch or one 108 is in engagement with contact 111, two

circuits are closed, one through solenoid wind ing 129 and the other through solenoid winding 162. I'nthe case of solenoid winding 129 its plunger is moved to bring connector 180 into contact immediately with contacts 181 with a' comparativ'el thus efiecting closing of the circuit of motor 17, while in the case of solenoid winding 162 its plunger ismoved slowly under the retardingaction of device 167 so as to give motor 17 time to adjust resistance 12' before: it

causes connector-165m bridge contacts166 .70

i x 180 to move away vfrom contacts 181.- hen the .air flow andsteam flow varied,

(After plunger 156 reaches the top of its movement, it 'again-Ibeginsto descend under 'tlie atio n-oithe retarding device 151 and afterla certain predetermined interval of time.- 'connector'121 again bridges contacts 120 and 122. "l f now contact 108 is in engagement with contact 111, which indicates that the steam pressure is still above normal and is either increasing or at least has not started to decrease, the circuit through solenoid wind- '-ing 129 will-be completed again, eifecting a secondzadjustment of the air by a predeter-- mined" amount, a's. already fexpiaip'ed; If, ho'we'v'emdurin' the'period tliafplunger 156 is,clescending,"t1e steam pressure'has started to. return toward normal, thereby moving contact 108 away from contactlll, thenan adjustment of the air will not take place.

-lVith the ',above-described arrangement, .therefore, it will be seen that'air adjustments are efi'ectedin small steps at predetermined intervals of time, the adjustments continuing untilthe tendency of the pressure'to increase has been overcome'and the pressure has started to return toward. normaL- :In connection with"'the operation just dc- Sm engagement with theflat portion of the cam on segment 130, Assume now that the increase in pressure is comparatively large so that the turning movement of shaft 102 is sufiicient to bring the rising portion of the cam surface on segment'. 130 un'der roller'131 so as to raise contact arm 132 and move contactl33 away-from contact 134. When contacts 133-and 131'are separated, the circuit through. theiwindings 147 of the magnetic -clutch is openedfsioi-that' plunger 156 is free 4 to move independently of themagnetic retarding device '15 "*As a result therefore,

y large increase in steam pressure, the retarding device'is disconnectedfrom plunger lfifi'and the plunger innuediately drops, bringingconnector 121 into air in the mannenalr'eady described, Also in. the manner-already described, plunger.

"156will be raised-again and-ifcontacts 133 and contacts 134 are still separated, then it will dropimmediately again-to efiect a sec ond adjustment of the air'providing contact 10.8 is still'in engagement with contact-111;,

.-.other, and contacts '108'and 111 remainin.

It follows, therefore, that as long'as contacts 133 and 134 are out of engagement with eachengagement with each other, a series of rapid be'movedaway fromcontact 111 whereupon no further air adjustments will occur.

I. adj ustments of the air will takeplace. However, as soon-asthe' pressure starts to.-re-. 'turn toward normalvalue, contact 108' Will' In this connection, it is pointed :out i that a boiler has considerable heat'storage capacity which tends to retarditsresponse to air-"and fuel changes so that while'a change in-air flow may be followed promptlyby a change in-therate at-whiclh steami-s being generated, stillthe change maylnot. be rapid;

' enough :to effect promptly-a restoration" of the press ure to normal value. =And particularly is this true where thepfressure change is ofcom arative-ly large-value. As a res' ult, in case: 0 a-comparatlvely largeincrease 1nsteampressure, the change in: the'air supply I Q .will notbe'gin-to effect an actualdecrease in 'the steam pressure, until possibly several successive adjustments have taken lace. However, as soon as the ressure egins to de- .crease, then because 0 theseveral successive adjustments which have occurred, the pres- .sure will continue to decrease until itreaches its normal value again. The' arrangement and ad ustment of the mechanism is so correlated with the lag of theboiler that for any i departure of the steam pressure from normal value the adjustments which occur will be such ordinarily as to bring the pressure back and the successive adjustments follow each, 110 other comparatively quickly. This serves to vary the supplyof air more rapidlyto correct to normal once the pointis reached at which the pressure begins to return toward normal value. Y

In connection with the operation of the device, the cam surface139 which actson arm 135, comes into action to determine the H1. pidity with which successive adjustments of the air will beeffected. It-will be seen that when plunger 156 is raised, cam 139'is moved Y away from. the arm 135 while. when theplunger is lowered the cam is-moved toward tends to come into action to move contact 134 may from contact 133 and whenever it moves 1 tntact 134 away from contact 133, magnetic retardingdevice151 is put out of actiondue to the circuit on windings 147 being opened If the departure is comparatively small as w ch. we to disconnect shaft142 r m shaft 144. If, for examplecam 139 moves 1 contact jl34iaway from contact .133 when.

plun er-156has-descended, one "half of its total movement, then it -will be' seen that the move fromeits uppermost position to its lowermost-position in one-halfthe time required .when the retarding device is in action during the entire downward movement, The instant when cam-139 comes intoaction to' separate contacts 134 and 133 dependsiipon liowrnuch the'cam' surface on segment 130 has-liftedcontact 133. If it has been lifted compara- V tive ly-h igh, the-result of a comparatively .large increase in pressure in header 4, then the retarding device willbe in action practiinterval be- 'tween successive adjustments of-the ail-depends upon the amount of the departure-of the pressure 111 header 4 from normal value.

iirst described, them the retarding device is m action all the time and the lnterval between successive ad ustments of the'air 1s comparatively' long. This serves to give the boiler time to respond to the first adjustment before a second adjustment occurs. If the departure is comparatively large as last explained, then the retarding device is inaction not at all pressure in header 4 from normal between 115 these two extremes, therewill be intervals between successive adjustments: of a duration depending upon the amountofthe departure, that is, on the-amount which cam segment 13.0, hasliftcdcontact 133. v

In connection with-the foregoing'it-will be seenthat if at first there is a comparative] y small departure-of the pressure from normal but that in spite of the first adjustmentlor I adjustments, the departure continues to m- 1'25; crease in value then-the time between succes-x siv'e adjustments will decrease'and will continue todecrease until such tune as the pres sure starts back toward normal value.

hen due to adjustments which'have taken 130- magnetic r'etai'din device willbein' action f during; the -first'haTf of, the movement of the plunger and will not. be in jaction during the second half. Asa result, theplungerwill 75 85 .cally not at all, plunger- 156,-fallirigv imme-' dia t ely to bring contact 121 into engagement I with. contacts and 122. On the other place, the steam pressure starts to return toward normal, value, that is, starts to de-. creasc, shaft 102 is' tur'ned in a counter- 1 clockwise direction and contact 108 is moved through spring arm 112 and solenoid 126 will not be closed because of the fact that the sprmg arm was moved off inset 1'14 and onto a I the insulated portion of disk 116 when bridge 1 109 turned in a clockwise direction duringthe former operation of the device.

\ windings and 32 being increased tea value- W'hen the pressure has returned to normal,

the parts will standin a position wherein contact 107 isin engagement with contact 110 a r from the boiler. Also it will'be seen that air ment with inset 114. v Y Assume now that the demand'for steam in creases so that there is an increase in the rate but wherein contact arm 112-is out of engageof steam flow from boiler 2.; This increase in steam flow is recorded immedlately QnsteaIn. flow'meter M, thecurrent through the steam.

flow meter circuit which includes solenoid corresponding to the increased rate of, steam flow. The pull of solenoid winding 30 on its plunger is thus increased-whereuponcontact 8 1is mo'vedinto engagement'with'contact 85. This serves to 'lo'sethecircaitfl eugnfi ld winding-79 of motor 78, operating it in a direction-to .turn contact arms 59 and 65' in a Q clockwise direction. This serves to increase theamount 'of'resistance'GO in the -field winding-9 of the motor .7, thereby decreasing the field strength and effecting an increase in the "speed of motor 7 and. hence an increase in the amount of fuel-be1ng fed-to the furnace;

At the same time arm moves in a direction to decrease the amount of resistance 66 in the' circuit including solenoid winding 69 thereby effecting an increasein the full of solenoid 69 on its plunger and a movement of contact 84 away .from contact 85. 'The fuel flow and steam flow are thus again brought to the de-- sired relation relatively to each other. The increase in steam flow which'has been assumed'to have taken place will be. accompanied by a decrease in the steam pressure in header 1, whereupon pressure responsive-device 100 will effect turning movement of shaft 102 in a counter-clockwise direction. This will effect-turning movement'of bridges .106

and 109, contacts 107 and 110 being in engage ment and as soon as contact arm 112 engages contact inset 114, a circuit will be closed through solenoid winding 12.6, whenever connector 121 again bridges contacts 120 and 122. This operation is similar to and will be understood from that already described in connection with solenoid winding 129. When the circuit is closed on winding 1'26, connector 172 thereupon bridges contacts 173 anda circuit is closed on field winding 18 of motor 17 which may be tracedas follows Line wire'22, conductor 174;, armature of mo-- tor-v 17, field winding 18, conductor 176, C011- tact arm 177, conductor 17 8, contacts 99, conductor17 9, contacts 173, and conductor 127 to is balanceddirectl against the rate ofstea'm fiow' fromnthe' boller so that-there will be supplied tothe furnace always an amount offuel sufficient to generate the steam flowing is supplied to the furnace to effect increase or decrease in the rateof combustion so as to maintain the steam pressure constant. In this connection, it will be understood that when a bpilerflis supplying steam to a steam consumption'device, the uniformity of the pressure "at which the steam is supplied totheconsumption device-is an indication of hoivnearly theheat supplied by the furnace 1 equals the heat required to generate the steam necessary to meet the requirements of the consumption device. A falling steam pressure'means'that'insuilicient heat is being supplied by the furnace to generate the required amountof steam, a; rising pressure means that too much heat is being supplied to gen'{ erate the required amount of steam, while a constant steam pressure means that the heat input 'is correct for .generating the required amount of steam. Adjustment of *the air supply irrespective of any immediate change in fuel sup ly serves promptly to vary the rate of com ustion'in the furnace. By adjusting the air supply, therefore, in accordance with the steam pressure so as to maintain the steam pressure constant andat the sametimecadjusting the fuel supply-to con-. form always to the-amount of steam actually being generated, efficient operation of the boiler is obtained.

. In addition to the foregoing, we provide also an arrangement for adjusting the rate of fuel supply soas tomaintain a desired -relation-between the rate-of steam flow and the rate of fuel supply andthe rate of steam? 'flowand the rate of air supply, thearrangement serving also to'ma'intain a fuel bed of the desired thicknessand' tov prevent at any time the airsupply being increased at too rapid arate;

Ifthe air flow is too great compared to the.

amount of steam being generated, solenoid windin 51 will overbalance the pull of, solenoid'winding 32 on lever 95 and turn lever 95 in a direction to move contact arm .7 2 toward the right, thereby increasing the amount of resistance 1 in the fuel circuit which indltion again but with 'a different ratio of fuel eludes solenoid winding 69. This serves to effect a .decrease in the amountof current flowmg n the fuel circuit and hence adecrease in the pullof solenoid winding 69 on theright hand end of lever-81. As a result contact 84 is brought into engagement with contact 85 to effect operation of motor 78.-in a direction to increase the speed of fuel supply motor-T and adjust resistance arm 65 to bring it to a'pcsitio'n such that the current through solenoid-'windn g-69 will be of a value suchthat the, pull of. solenoid winding 69 will again' balance the pull of solenoid winding 30, contact 84fbeing then moved from engagement with contacts 85. I This gives a balanced con air flow is too small compared to the amount. of steam being generated, then solenoid-winding32 will overbalance the p'ullof solenoid windingfil on lever 95 thereby turning lever 72 toward the left and decreasing the amount ofresistartce 71 in the fuel circuit whereupon" the rate of fuel supply is decreased in a man ner similar to that just described.

Assume that the boiler is operating and that there occurs an increase in demand for steam ofsubstantial amount, so that the boiler cannot supply it without first, building up both the fuel supply and the air supply to a considerable *extent. Under these circumstances, the steam pressure may be decreased by a considerable. amount whereupon there will ban tendency to effect rapid, successive 35' the fuel supply to the creased onl as fast as the rate of steam flow, increases, 11 the operationof a stoker fired furnace, there is'a certain amount of lag in these circumstances, the arrangement com-l adjustments of the air. O n the other hand,

' serves to thicken the 'fuel bed, this being a desirable thing upon increase in boiler load.

r This result isaccomplished'due to the fact -tliat theincreased a r flow causes solenoid windingjito overbalance solenoid winding 32, thereby movin contact arm 7 2 toward the right to increase t e amount of resistance 71 m the. fuel'circuit. This'results in decreasing the current in the fuel circuit, thereby weak,- ening'the-pull'ofsolenoid 69and permitting solenoim to hold contact 84 in engagement with contact 85'when' otherwise the steam flow 4 --would not be'suflicient to effect this result; Fuel is thus suppliedto the furnace temporarily at ,a rate greater than that necessary for generating the steam flowing from,

the boilersothat the fuel bed gradually thickfurnace will be in efuel and air and obtain immediate ens. If, as the result of successive adjustments of the steam pressure responsive mechanism, the airfiow increases, to .a value too great as comparedcwith the steam flow, then pin 97 willengage'connec'tor 98 and move it away from contacts 99. This opens the 'cir cuit 'of field winding 18 and motor17 and prevents further adjustment ofrheostat 12' for motor 11 until the fuel supply and the v steam flow have had an opportunity to build up'. By this arrangement, the air supply is prevented from building up at a rate so rapid I that it might blow the fire full of holes. I In: case the demand for steam'decreases by a considerable amount, which means that the rate of fuel supply and the rate of air supply .should be substantially decreased, then under these circumstances, when, several successive noid winding 32 "will overcome the pull on adjustments of the air have taken place, sole solenoid winding 51, thereby moving contacti arm 72 toward theleft. This serves to reduce the amount of resistance in the fuel. circuit,

thereby strengthening the current in the fuel' circuit andmoving contact 82 into engage- '--ment with contact 83, thereby decreasing the" rate at which fuel is .beingsupplied to the v furnaces; or, on the other hand, if contact 82 J is in engagement with contact 83 already as a result of a decrease in the steam flow, then the contact 82 will be held in engagement with contact 83 for a period longer than would be the case otherwise, so as to continueto reduce the rate of fuel supply evenafter the steam flow has reached a value corresponding to the fuel supply for such steam value. This serves to temporarilyfsupply fuel to the furnace at. "a rate slower than it 'is being burned which results in a decrease of the thickness of the fuel bed. v Y From a consideration of the foregoing, it will be seen that the mechanism operates to maintain automatically the desired fuel bed thickness.

-Assume'that the boiler is operating at a certain load, that everything is in balance, and

that the quality of the fuel supplied to thefurnace improves. This will cause an increase in the steam pressure in conduit 4 whereupon the pressure responsive device 100 will operate to. decrease the amount of air supplied to the furnace. -Due to the de-' creased amount of'air,'so1enoids-32 and 51 will become unbalanced and contact arm'72 will-be moved to the left therebycutting some of the resistance 71 out of the fuel circuit. In the manner already described, this will eifecta decrease in the amount of fuel supplied to the furnace-t0 bring about a new -fuel-air ratio of a; value economical'for the increased and'the supply of air decreased to again bring about a new fuel-air ratio which 'new grade of fuel. On the other hand, if the 4 quality of ,the fuel gets poorer then in acor responding manner; the supply of fuel will be will efiectburning ofthe' If. the fuel gets, larger in size, the fuel bed poorer quality: of fuel economically,

' resistance decreases whereupon more airwill flow throughfit. This-increase in air flow will b e decreased which will result temporarily decreasing the rate of fuel supply untll the fuel bed is thinned so that the desired amount of airwill'flow through it.

It holes occur in the fuel bed, ai'r'fiow meter N will register too much air relatively to th'e steam flow whereupon the rate of fuel supply will be increased temporarily until the holes are filled up.

' Should the air flow increase-too much relatively to the steam fiow, .then finger 97 will move connector-98 away from contacts 99, thus opening thecircuit through conductor 179 and preventing any increase in the air supply if, due to the holes in the fire bed there should occur a drop in the steam pressure.

Soot or tubes will cause air flow meter N to register more air than it would if the boiler tubes were clean eventhough no more air is actually flowing; This is due to the higher resistance of the boilerjtubesto the air passing over them which causes a greater pressure drop across the tubes. As a result solenoidw ndings 32 and 51 will become unbalanced in a direction to increase the rate of fuel supply brought about by the fact that the decreased relatively to therate of air supply to make up, for the slightly lower boiler efiiciency due to the dirty boiler. I

Scale on the inside of the boiler means that for a given quantity ofair the steam will not be generated that should be which means that the fuel flow must be increasedsomewhat relatively to the steam flow This result is steam flow relatively to the air flow results in an unbalance of solenoid windings 32 and 51, the pull of solenoid winding 32 being.

slightly weakened, so that solenoid winding 51 pulls contact arm 72 toward the right thus cutting more of resistance 71 into circuit and so increasing the rate of fuel supply in the manner already explained. a

Any change in operating condition of the boiler other than demand for steam which causes a change in steam pressure acts through device 100 to efiect a change intlie air flow thereby unbalancing solenoid windings 32 and 51, thus effecting a corresponding adjustment in the rate of fuel flow.

From a consideration of the foregoing, it

will be seen that the balanced relay arrangeslag on theouts ide of the boiler ment comprising solenoid windings 32 and 51 operates to maintain'always an economical ratio between the .fuel" and air under varying operating conditions- For this reason, the arrangement may betermed an efliciency deeflicientoperating conditions. The adjustments of the, fuel required due to changes which effect an unbalance of solenoid windings 32 and 5l are not large and under ordinary conditions will not amount to more than- .vice'in that itfunctions to maintain always about 10%. Resistance 71, therefore, is I chosen of a value such that the total changes in fuel flow whichmay be efiectedby a is of the order of 10%. Onith'e other hand,re'siste0 ances-GO and-66 must be of values such thatthey may-efi'ect'change in fuel flow over the 1 entire range of operation of the furnace.

In-acoordance with the provisions of the patent statute, we have described the principle of operation of our. invention,-together-- with the apparatus which we now-consider to.

represent the best embodiment thereof, but

we desire tohave it understoodfthat the appa- 'ratus shown is onlyillustrative andthat .the -1I1V8nt1011 may be carried out by other means;

What we claim as new and desire to secure by Letters Patent of the United States, is 1. The combination with a boiler, of means for. supplying combustible thereto, means responsive to'departure of an operating condition ofthe boiler from normal value for effecting success1ve-ad ustments of the com- "bustible supplying means, and means-whereby the length of time between successive adjustrnents is governed by the extent of the departure of theoperating'condition from. its

normal value. 5 H

2. The combination with a boiler, ofm'eans fgr supplying combustible thereto, means responsive to departure of an 'opcrating-Icon dition ofthe boiler from normal value for effecting successive adjustments of the com bustible supplying means, and means whereby' the timebetween successive adjustments becomes shorter as the operating 'conditio'n i.

departs further from its normal value.

3. The combination with a boiler, of means for vsupplying combustible thereto, means. responsive .to departure of an operating con dition of the boiler from normal value for combustible supplying means, and means controlled by'the amount which the operating. condition has departed from normal for determining the time between successiveadustments.

effecting successive unit adjustments of the 'i A, The combination with'aboiler, of means for supplying combustible thereto, means including an electric circuit and a circuit closer for eflecting adjustments of the com-- bustible supplying means, means operable upon the departure of an operating condi tionv of the boiler from normal value for rendering said circuit closer operable to effect successive unit adjustments of the combussecond circuitcloser means, retarding means tible supplying .means,.and means controlled for delaying the closing of said second cirby the amount which the operating condition c'uit closing means, and means responsive to has departed from normal for determining the extent of the departure of the operating A 5. The combination with a boiler, of means condition'of the boiler from normal value,

the time between successive adjustments.

retarding means is in operatiom 10. The combination with a boiler, of means for supplying combustible thereto, motor means for adjusting, the combustible supplying means, an electric circ'uitwhich condition of the boiler from .normal value for determining the period during which when closed effects movement of said motor a second circuit closer in said circuit-which means, a circuit closer means in said circuit is closed at successive intervals,'and' means which is closed upon the departure of an controlled by the amount which the operatoperating cond tion ofthe boiler from noringcondltion has departed from normal for mal value, a second circuit closer: means 1n determining the length of the successive intervals. 1 x

6. The combination with a boiler, of means for supplying combustible thereto, means said circuit, means foreffecting-successive closures of said second circult closer means, retarding means for delaying the closing of said second circuitclosing means, and means.

responsive to departure of an operating confor progressively increasing the period durf dition of'theboiler from normal value for ing which said retarding means is inoperaeffecting successive adjustments of the comtion as the operating condition departs furbustible'supplying means, and means for pro thenfrom normal value. gressively decreasing the interval between successive adjustments as the value of the boilers operating in parallel, of means for operatin'g; condition departs further fromsupplying combustible to each boiler, normal value. responsive to an operating condition appur -7. The combination with'a boiler, of means tenant toall the boilers for effecting succesforsupplying combustible thereto, motor sive adjustments of all the combustible sup- 'means for adjusting the combustible supplyplying means, and means whereby the length ing means, an electric circuit which when oftime between successive.- ad ustments 1s 2 closed effects movement of said motor'means, governed by the extent of the departure of condition of the boiler from normal value, a

a circuit closer means in said circuit which is the operating condition from ;:its normal closed upon the departure of an operating value. r v

' 12. The combination with a boiler, of second circuitcloser means in'said circuit, means for supplying combustible thereto,

and' means for eiiecting successive closures means 'SPO S G t0 d par of an op i g of said second circuit closer meanscondition of the boiler from normal value 8. The combination with a boiler, of means for eifectlng successive substantially equal for supplying combustible thereto, motor unitadjustments of said combustible supplymeans for adjusting the combustible supplying means, and means whereby said succes ing means, an electric circuit which when sive unit adjustments are caused to occur at closed efi'ects movement of said motor means untervals of predeterm ned duration. a circuit closer means inrsaid circuit which 13. The combination wlth aplurality. of

- is closed upon the departure of an operating .boilers operating in parallel, of means for diti f f th boil f normal l e, supplying (70Il'lblISt1ble,t0 each boiler, means a second circuit closer means insaid circuit, respo w PQ Pfi g n ion app rme'ans for effecting successive closures of said tenant to l. he bollers for eifectlng sucsecond circuit closer means,'and means recessive unit adjustmentsof all the combustisponsive to the extent of the departure of l upp ying pieansandmeans whereby said the operatingcondition. of'the boiler from successive unlt adjustments are caused to Y normal value for determining the period of Occur at intervals ofpredetermined duration.

circuit closing means.

14. The combination with a boiler, of meansfor supplying air and fuel thereto,

9; Th bin ti ith a b il of means comprising an air circuitin which is for supplying combustible thereto, motor effected a flow of current proportional to the means for adjusting the combustible supply- E QPPLY, 111611115 P S g ll fi ing means, an electric circuit which when WhICh-IS efiecttid flow 9 Current P QPP l d ff t mo t f id motor means, tional to the fuel supply, means comprising a circuit closer means in said circuit which it 1 Circuit in which s effec ed a flow of time between successive closures of the second is closed u'pon'the departure of an operating current proportional to the rate of flow of condition'of the boiler from-normal value, vapor from the boiler, and means actuated second circuit closer means -'in said circuit, by the currents in said circuits for ad usting means for effecting successive closures of said the fuel supplying means to maintain a premeans/ 11. The combination with a plurality at determined relation betweenthe current flowin'the air current "and the vapor circuit and f in the fuel .circuitand the vapor circuit.

I15. The-combination with'a boiler, of

the air supply, .means comprising a fuel cir cuit in'which is 'eifected'a flow of current proportional to the fuel. supply,'means comprising a vapor circuit in which is-efi'ected a flow'.

of current proportional to the rate. of flow of vapor from the boiler,'means responsive to' departure of an operatingcondition of the boiler from normal value for, effecting adjustment'of the airsupplying means, and

means actuated by the currents in said cir-- cuits for adj ustingthe fuel-supplying means tomaintain'a predetermined relation between tliecurrent flow in the fuel circuit, and the current flow in the'vapor circuit;

16. The combination; with-a. boiler, of means for-supplying air and fuel'thereto, means comprising an air circuit in which is effected a flow of .current proportional to the airf supply, means comprising a fuel circuit in which is efiected'a flow of current proportional to the fuel supply, means comprising avapor'circuitin which-is effected a flow of current proportional t0 t;l1e rate of flow of ii vapor from the boiler, means responsive to departure of'an operating conditionof the,

boiler from normal value for efiecting successive unit adjustments of the air supplying means, and means. actuated by theflow of currents in said circuits foradjusting the fuel supply in accordance with the flow of vapor from the boiler. z

17. The combination with a boiler, of means for supplying air and fuel thereto, means'comprising-an air circuit in Which-.is

effected a flow of current proportional to the air supply, means compris ng-a fuel circuit in 'which is effected a flow of current proportional to the fuel supply, means comprising a vapor circuit in which is effected a flow of current'proportional to the rate'of flow of vapor from the boiler, means responsive to "departure of an operating condition of the boiler from normal value for efi'ecting successive unit adjustments of the air supplying means, meanswhereby the. length of time between successive adjustments is governed bythe extent the departure of the operating condition from its normal value, and means actuated by the fiow of currents in said-circuits 1 .for. adjusting the fuel supply in accordance with the flow of vapor from the .boiler.

18. The combination with a, lurality of boilers operating in parallel, of means for supplying'fuel and" air to each boiler, means responsive to an'operating condition appurtenant to all the boilers for effecting successive unit adjustmentsof all the air supplying means, means whereby said successive unit of predetermined duration; and means for .1

- effecting adjustment of the fuel supplied to 'e a'ch boiler in accordance :with the-flow of means forIsupplying'ilir and-fuel thereto,l' .means comprising an air: circuit which is eflected a flow of current proportional to vaporfrom Such boiler/f fi 19. The combination-witha plurality of pin-tenant to-all theboilers or effecting successive unitad ustments of all the air supplyin means, means whereby the length of .tn'ne etween successlve unit ad ustments is govere'ned by the extent of the departure of the operating condition from its normal value,-and ineansfor effecting adjustments of the fuel supplied to each boiler in accordance with the flow of vapor from such boiler.

20.. The combination'with a' plurality of, bo lers operating in parallel, of means for supplying fuel and air'to each boiler, means responsive to an' operatin 'condition eppurtena-nt to all the boilers for effecting sue? cessive unit adjustments of all the air 'supplying means, means whereby said'successive unit ad ustments are caused to occur at intervals of predetermined duration, and means i for maintaining for each boiler a desired ratio between the fuel supplied to and the vapor flow ng from each individual boiler.

21. The combination with a boiler having fuel supplying means, air supplying means,

and means responsive to an operating-condition of the boiler for controlling automatically said supplying means, of means forming a part of said automatic controlling means for effecting increase and decrease 1n the fuel bed'thickness with increase and decrease in the load onthe boiler. I

22. The combinationwwith a boiler having fuel supplying means and air supplying.

means, of means responsive to the pressure in the boiler for adjusting the air supplying l means only; and means responsive to resultmg changes 1n the rate of flow of vapor from the, boilerfor adjusting the fuel supplying Y means.

23. The combination with a boiler having fuel supplying means and air supplying means, of; means responsive to an operating condition of theboiler for adjusting the air supplying means, means responsiveto the rate of flow of vapor from the'boiler foradjusting the fuel supplying means, and means for preventingjthe ratio of air flow to vapor flow from exceeding a predetermined value.

24. The combination with a boiler having fuel supplying means "and air supplying means, of means res )onsive to an operating condition of the boi er for adjusting the air supplying means, means responsive to the rateof flow of vapor from the boiier for adjusting the fuel supplying means, and means for effecting a temporary increase or decrease in the rate offfuel supply to the boiler when theratio of vapor flow to air flow passes certain limits.

25. The combination with a batteryof boilers each having a fuel supplying means A and an air supplying means, of'means responsive -to an operating condition appurtenant to all the boilers for adjusting the air supplying means of all the boilers, and means responsive to-the rate of flowvof generated vapor from each individual boiler for 'ad-" justing its fuel supplying means.

26. The combination with a battery of boilers each having a fuel supplying means and an air supplying means, of means responsive to an operating condition appurtenant to all the boilers for adjusting the air supplying means of all the boilers, means responsive to the rateof. flow of vapor'from each individual boiler for adjusting its fuelsupplying means,-and means associated with each boiler for preventing the ratio of air v flow to vapor flow from exceeding a predetermined value;

27. The combination with a boiler, of

means for regulating the rate of air supply to the boiler in accordance with the pressure of the vapor flowing from the boiler and means for regulating the rate of fuel supply to the boiler in accordance withtheirate of flow of vapor from theboiler. 28..The "method of automatically regulating the supply offuel and air to a boiler,"

I which comprises regulating the air. supply only in response too such pressure constant, Land regulatin the fuel supply to correspond'to the rate 0 flow of vapor from the boiler.-

only in response to changes in pressure 0 ing the fuel supply inaccordance wit the ratio of vappr flow to air fiow.

30. The method of operating a boiler which comprises adjusting the fuel supp] in accordance with the rate of vapor flow roin the boiler, and adjusting the air supply solely in accordance with the vapor ressure.

In witness whereof, we ave hereunto set our hands this 2nd day of December, 1926. FRANK S. BENNETT. LEONARD R. BIGGS.

anges in pressure of the a vapor flowing from e-gboiler to maintain 

